This book undertakes a general review on the major infectious diseases in Hong Kong and Mainland China. Secondly, it will set out the future directions for better preparedness in the fight against infectious diseases particularly the emerging new infections in the 21st Century. It also discusses the severe acute respiratory syndrome (SARS), also called infectious atypical pneumonia in China, is an emerging infectious disease caused by a novel variant of coronavirus (SARS-associated coronavirus, SARS-CoV). It is mainly characterised by pulmonary infection with high infectivity and fatality. SARS swept across almost every continent of the globe, and has currently involved 32 countries and regions, including the mainland of China, Hong Kong, Taiwan, North America and Europe. The condition is hard especially in China. Chinese scientists and healthcare workers co-operated closely with scientists around the world to fight with the disease. On April 16, 2003, World Health Organization (WHO) formally declared that SARS-CoV was an etiological agent of SARS. Currently, there is no specific and effective therapy and prevention method for SARS. However, this disease can be prevented, and it is also curable and controllable. The main treatments include corticosteroid therapy, anti-viral agents, anti-infection, mechanical ventilation and medical isolation. With the endeavour of the Chinese Government, medical staffs and other related professionals, SARS has been controlled in China. Scientists around the world, including Chinese scientists have made a great progress in SARS research from that time on. A review is presented of the history of SARS and the progress in SARS research, especially in China.